This invention relates generally to systems and methods for manufacturing multiple conductor electrical cable. More particularly, the invention relates to systems and methods for manufacturing multiple conductor electrical cable that exhibits an improved crosstalk margin relative to industry standards, as well as cable produced by such systems and methods.
Multiple conductor electrical cable for use in applications such as telecommunication and communication between computers are well known. Nevertheless, the increases in transmission rates, measured in bits of information per second, required to transmit large amounts of information at high speed severely tax the capabilities of conventional multiple conductor electrical cables. For example, computer communications using data rates of more than one gigabit per second are now contemplated using inexpensive twisted pair electrical cable, rather than more expensive transmission media such as coaxial cable. Transmission rates of the order of a gigabit per second have been considered excessive for systems that rely on twisted pair copper conductor cable, based on high levels of electromagnetic interference that were expected to be encountered. Recent advances in electronics have created a need for cable that can accommodate high transmission rates, such as a gigabit per second, with acceptably low noise, low crosstalk, and low cost.
While multiple conductor electrical cable, including twisted pair cable, has been in use for many years, there are significant problems in making twisted pair cable that can perform within the requirements of technical standards such as TIA/EIA-568-A Commercial Building Telecommunications Cabling Standard, known as Category 5e, the disclosure of which is incorporated herein by reference in its entirety. Extended lengths (for example, greater than 100 meters, or approximately 328 feet) of twisted pair cable made by the methods of the prior art often fail to satisfy the Category 5e standard. However, for a cable manufacturing method to be useful, one must routinely satisfy the standard of performance for cable that exceeds a length of 100 meters or even a length of 1000 meters.
The present invention provides systems and methods for manufacturing multiple conductor electrical cable with improved transmission parameters, for example, reduced crosstalk, than is possible using the systems and methods of the prior art. The multiple conductor electrical cable produced using the systems and methods of the invention exhibits both improvements in the transmission parameters and reductions in the variations in the transmission parameters that control the quality of the transmission as compared to cable manufactured without the systems and methods of the invention. For example, cable made according to the teachings of the invention exhibit increased margins by which the transmission parameters exceed the requirements specified in Category 5e, as compared to cable made without the systems and methods of the invention.
Some of the advantages that the systems and methods of the invention provide include higher quality multiple conductor electrical cable, greater assurance that manufactured cable will meet or exceed the specifications required to conform to an industrial standard (e.g., that the cable will be acceptable for use, or xe2x80x9cmerchantablexe2x80x9d), higher rates of production, and lower incremental costs to implement the systems and methods of the invention.
In one aspect, the invention features a multiple conductor cable that includes a plurality of elongate conductors disposed in a predefined mutual mechanical alignment. This mutual mechanical alignment is calculated to provide a cable that includes at least one transmission parameter optimized with respect to Category 5e. The mutual mechanical alignment of the cable is defined by a rate of advance of at least one of the conductors through a rotatable alignment die and a rate of rotation of at least one of the conductors substantially about its elongate axis. In some embodiments, a binder may be applied to the plurality of conductors.
In one embodiment, the invention may include the multiple conductor cable in which at least one transmission parameter selected from the group of transmission parameters consisting of input impedance, characteristic impedance, resistance unbalance, mutual capacitance, capacitance unbalance to ground, capacitance unbalance to shield, attenuation, Near End Cross Talk (xe2x80x9cNEXTxe2x80x9d), Power Sum NEXT, Equal Level Far End Cross Talk (xe2x80x9cELFEXTxe2x80x9d), and Power Sum ELFEXT is optimized with respect to Category 5e.
In another embodiment, the invention includes the multiple conductor cable in which the mutual mechanical alignment is calculated to provide a cable including a NEXT that exceeds the NEXT specified in Category 5e as expressed in Table I below by no less than 2 decibels, more preferably no less than 5 decibels, and most preferably no less than 10 decibels.
In some embodiments, the invention comprises a multiple conductor cable including a binder in which the binder may be a tubular sheath, a helical wrapping, a longitudinally slotted sheath, or an array of individual ties. In some embodiments, the invention comprises the multiple conductor cable in which the binder is made from a material that is heat shrinkable, is flame retardant, and/or is a thermosetter.
In some embodiments, the invention includes a multiple conductor cable that has a single twisted pair of conductors, or that has multiple twisted pairs of conductors.
In some embodiments, the invention includes a multiple conductor cable that has a mechanical alignment component that is incorporated into the cable to stabilize the mutual mechanical alignment of the conductors. In one embodiment, the mechanical alignment component may have a finned configuration and the fin(s) may be positioned substantially parallel to the length of the mechanical alignment component. The fin(s) may be conductive, or, alternatively, the fin may be non-conductive.
In another aspect, the invention features an apparatus for manufacturing a multiple conductor cable from a plurality of elongate conductors. The apparatus includes a rotatable aligning die that includes a plurality of apertures. The apparatus includes an applicator that can apply a binder to the plurality of conductors. The apparatus may have one or more motors that cause the plurality of elongate conductors to traverse along its elongate axis, and that also cause the plurality of elongate conductors to rotate substantially about its elongate axis. The apparatus causes the plurality of elongate conductors to traverse at least one of the apertures of the aligning die. The apparatus causes the elongate conductors to be brought into a defined mutual mechanical alignment. The elongate conductors may be retained in a mutual mechanical alignment, at least partially, by the application of the binder.
In some embodiments, the invention includes an apparatus that has a support situated substantially along a rotation axis of the die. The support stabilizes the mutual mechanical alignment of the plurality of elongate conductors. In some embodiments, the support traverses the rotational die and is incorporated into the cable that is manufactured.
In one embodiment, the invention includes a support fixture that can adjustably position the binder applicator relative to the position where the elongate conductors are brought into mutual mechanical alignment.
In some embodiments, the apparatus includes a binder applicator adapted to dispense a binder material that can bind the plurality of conductors together.
In one embodiment, the invention includes a rotatable aligning die that includes a rotatable body that includes a circular periphery and a plurality of apertures through the rotatable body. Each of the plurality of apertures is adapted to receive one or more elongate conductors. The apertures are aligned in the rotatable body substantially transversely to a plane defined by the circular periphery of the rotatable body. The rotatable aligning die also includes a fixing collar that can be adjustably attached to the apparatus for manufacturing a multiple conductor cable. The rotatable body is capable of rotating relative to the fixing collar. The rotatable aligning die may include at least one ball bearing situated at the circular periphery of the rotatable body and supporting the rotatable body within the fixing collar.
In another aspect, the invention features a rotatable aligning die for the manufacture of multiple conductor electrical cable, including a rotatable body that includes a circular periphery and a plurality of apertures through the rotatable body. The apertures are aligned in the body substantially transversely to a plane defined by the circular periphery of the body. Each of the plurality of apertures can receive one or more elongate electrical conductors. The rotatable aligning die includes a fixing collar that can be adjustably attached to an apparatus for manufacturing a multiple conductor cable. The rotatable aligning die includes at least one ball bearing situated at the circular periphery of the rotatable body. The ball bearing(s) support the rotatable body within the fixing collar. The rotatable body can rotate relative to the fixing collar. The application of rotational force to at least one of the electrical conductors causes the rotation of the rotatable body.
In another aspect, the invention features a process for manufacturing a multiple conductor cable from a plurality of elongate conductors. The process includes the step of providing a rotatable aligning die that includes a plurality of apertures, and providing an applicator that can apply a binder to at least two of the plurality of conductors. The process includes the steps of advancing at least one of the plurality of elongate conductors through at least one of the apertures of the aligning die, and rotating at least one of the plurality of elongate conductors about its elongated axis. The process includes the step of bringing the plurality of elongate conductors into a defined mutual mechanical alignment. The process includes the step of retaining at least two of the plurality of elongate conductors in the mutual mechanical alignment at least partially by the application of the binder.
In one embodiment, the invention includes the step of providing a consumable mechanical alignment component that is incorporated into the cable to stabilize the mutual mechanical alignment of at least two of the plurality of conductors. In another embodiment, the invention includes providing a support member disposed substantially along a rotation axis of the aligning die to stabilize the mutual mechanical alignment of at least two of the plurality of conductors.
In another aspect, the invention features a multiple conductor cable including a plurality of elongate conductors produced by the process described above.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following drawings, description, and claims.